Process for separating and recovering hydrogen fluoride from mixtures

Abstract

A process is disclosed for the liquid phase separation and recovery of hydrogen fluoride from a mixture comprising hydrogen fluoride and a fluorinated organic hydrocarbon. The process requires that the mixture be treated with a sufficient amount of a coupled phase-separating agent comprising an organic or inorganic salt, an alkanolamine or mixtures thereof and a substituted or unsubstituted aromatic compound to form a first and a second phase. The first phase that is formed is a hydrogen fluoride-rich phase that additionally contains substantially all of said salt, said alkanolamine or mixtures thereof from the coupled phase-separating agent. The second phase comprises substantially all of said aromatic compound and the fluorinated organic hydrocarbon. It is substantially free of hydrogen fluoride. The phases are separated from each other. Hydrogen fluoride and the salt, alkanolamine or mixtures thereof are then recovered from the separated first phase and the aromatic compound and fluorinated organic hydrocarbon are recovered from the separated second phase.

I claim: 
     
       1. A process for the liquid phase-separation of hydrogen fluoride from a mixture comprising hydrogen fluoride and a fluorinated aliphatic hydrocarbon comprising adding to the mixture an amount of a coupled phase-separating agent comprising an organic or inorganic salt, a lower alkanolamine or mixtures thereof and a substituted or unsubstituted aromatic compound, the amount of said coupled phase-separating agent added being sufficient to form a liquid first phase comprising hydrogen fluoride and substantially all of the organic or inorganic salt, lower alkanolamine or mixtures thereof and a liquid second phase, said liquid second phase comprising substantially all of said substituted aromatic compound and being substantially free of hydrogen fluoride and rich in said fluorinated aliphatic hydrocarbon. 
     
     
       2. The process according to claim 1 wherein said fluorinated aliphatic hydrocarbon is a compound of the formula   CH.sub.a F.sub.3-a --CH.sub.2 --CH.sub.b F.sub.3-b     wherein a is 0 or the integer 1 or 2 and b is 0 or the integer 1, 2 or 3.   
     
     
       3. The process according to claim 1 wherein said salt is an a C 1  -C 4  alkylammonium or Group Ia cationic salt of an organic acid and said aromatic compound is benzene or phenyl substituted with at least one substituent selected from the group consisting of halo, C 1  to C 6  alkyl and halo substituted C 1  to C 6  alkyl. 
     
     
       4. The process according to claim 3 wherein said organic acid is selected from the group consisting of a carboxylic acid and a sulfonic acid and said aromatic compound is chlorobenzene. 
     
     
       5. The process according to claim 4 where organic acid is selected from the group consisting of difluoroacetic acid and trifluoroacetic acid. 
     
     
       6. The process according to claim 4 wherein said organic acid is selected from the group consisting of C 1  -C 4  alkylsulfonic acid, unsubstituted and C 1  -C 4  alkyl-substituted aryl sulfonic acid and halosulfonic acid and said aromatic compound is chlorobenzene. 
     
     
       7. The process according to claim 1 wherein said salt is a C 1  -C 4  alkylammonium or Group Ia cationic salt of an inorganic acid. 
     
     
       8. The process according to claim 7 wherein said inorganic acid is selected from the group consisting of hydrofluoric acid, hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid and said aromatic compound is chlorobenzene. 
     
     
       9. The process according to claim 1 wherein said temperature and pressure of the treated mixture is sufficient to cause the first and second phase to remain as liquids. 
     
     
       10. The process according to claim 1 wherein said coupled phase-separating agent comprises a lower alkanolamine and chlorobenzene. 
     
     
       11. The process according to claim 1 wherein said coupled phase-separating agent comprises a compound of the formula [HO--(CH 2 ) x  ] y  NH z  where x is 1 to 6, y is 1, 2 or 3, z is 0, 1 or 2 and the sum of y and z is 3 and chlorobenzene.   
     
     
       12. The process according to claim 1 wherein said coupled phase-separating agent comprises sodium fluoride and chlorobenzene. 
     
     
       13. The process according to claim 1 wherein said coupled phase-separating agent comprises ethanolamine and chlorobenzene. 
     
     
       14. The process according to claim 1 wherein said coupled phase-separating agent comprises diethanolamine and chlorobenzene. 
     
     
       15. A process for the liquid phase-separation of hydrogen fluoride from a mixture comprising hydrogen fluoride and 1,1,3,3,3-pentafluoropropane comprising adding to the mixture an amount of a coupled phase-separating agent comprising an organic or inorganic salt, a lower alkanolamine or mixtures thereof and a substituted or unsubstituted aromatic compound, the amount of said coupled phase-separating agent added being sufficient to form a liquid first phase comprising hydrogen fluoride and substantially all of the organic or inorganic salt, lower alkanolamine or mixtures thereof and a liquid second phase, said liquid second phase comprising substantially all of said substituted aromatic compound and being substantially free of hydrogen fluoride and rich in 1,1,3,3,3-pentafluoropropane. 
     
     
       16. The process according to claim 15 wherein said phase separating agent comprises sodium fluoride and chlorobenzene. 
     
     
       17. The process according to claim 15 wherein said phase separating agent comprises diethanolamine and chlorobenzene.